Researchers build miniature flying robots, modeled on Drosophila

Piezoelectric muscles flap tiny, gossamer wings.

It's relatively easy to get something big and heavy to fly. With enough equipment, it's possible to load the object with lots of energy to power the flight, specialized parts to control it, and the computers (or people) needed to direct the flight. But things get challenging as you make things smaller, and it gets harder to squeeze all the requisite parts into an ever-shrinking space. In that, nature has us beat, since something like a fruit fly crams all the energy, control systems, and specialized hardware into an extremely compact form.

We may not be at fruit fly level yet, but researchers are giving the insects some competition. Today's issue of Science reports on miniature flying robots that aren't much bigger than a coin. The power and control are handled externally, but the tiny robots can still perform basic maneuvers, and they have enough lift to spare that they could fly under their own power for a few minutes if the right power storage were developed.

The authors are all from the Wyss Institute for Biologically Inspired Engineering at Harvard, and they clearly find insects inspirational, noting that, despite their simple nervous systems, "flying insects are able to perform sophisticated aerodynamic feats such as deftly avoiding a striking hand." So they set out to build their own.

Simply scaling down mechanics that work for flight on larger objects wouldn't do. Scaling things down just results in too little force, or it creates a situation where surface interactions between the parts inhibit flight, as things like friction begin to dominate. Rather than taking the traditional route to get something tiny aloft—attaching it to some form of rotary engine—they returned to the fly for inspiration, making a pair of flapping wings.

On the fly, the wings work because the angle they take when moving upwards is different from the one they take when flapping down. The authors set that up so it happened passively; as the wings swept in opposite directions, the hardware at the joint where they met the robot's body forced them to rotate.

To get the wings to beat fast enough, the authors created two "muscles" made from a piezoelectric material, which changes shape when a voltage is applied. These flapped the wings at 120 beats a second. Not only is this rate similar to a fly's, but it also created a resonance in the robot's body that amplified the force of each beat. That resonant frequency was so important that the flight control system never changed it, even when it needed to change the force generated by the wing (to fly up or drop lower, for example). Instead, the force was controlled by changing how far the wing traveled with each beat.

That same approach allowed the researchers to rotate their robot while in flight. By having the left or right side do a stronger beat, the robot would turn.

The robot takes flight.

All of this, however, meant that the robot was very dynamic while flying. The control system, which was connected via the same wires that supplied power, had to make constant adjustments to keep it stable. To enable that, the robot had a number of silvery spheres on appendages. These helped with balance and could be tracked by a motion capture system that used them to figure out the robot's position in a three-dimensional space. Overall, the control system's response time was about 12 milliseconds—just a hair slower than a fly's.

Thanks to a carbon fiber body and polymer wings, the whole package weighed only 80 milligrams. Its three centimeter wingspan allowed it to generate upwards of 1.3 milliNewtons of force.

Overall, it's an impressive little device. But we're still a long way off from being able to put the computing power that keeps it stable onto the robot itself. And even if all its spare lift capacity went into batteries of some sort, it would only be enough to allow it to fly for a matter of minutes. For now, millions of years of evolution have the engineers beat.

62 Reader Comments

The power and control are handled externally, but the tiny robots can still perform basic maneuvers, and have enough lift to spare that they could fly under their own power for a few minutes, if the right power storage were developed.

The mechanics developed are neat, but like the article stresses, this is the hard part. The cpu cycles for adequate control will come in a nice neat tiny package in very short order, I think, but I am pessimistic about an adequate and appropriate power source being developed in our lifetimes, if progress up to now in the field is any indicator

The robot engineers are getting better at mimicking nature on things like wing movements; now they need to figure out how to mimic nature on the energy situation. Artificial metabolism with a small, light food supply perhaps?

...I am pessimistic about an adequate and appropriate power source being developed in our lifetimes, if progress up to now in the field is any indicator

Wireless power such as laser, for instance, might work well for this type of application...depending on what the application for micro-flight there might be...

That is a good idea, but those applications would be limited to whatever the effective range and line of sight would be for such a power source. Indoors, I suppose I could imagine some pervasive induction field that would power them, but, again, that limits your applications.Photonic Photoelectric? Maybe, but weight and (lack of) surface area would be an issue I imagine. Like I said, power is the really hard part.

...I am pessimistic about an adequate and appropriate power source being developed in our lifetimes, if progress up to now in the field is any indicator

Wireless power such as laser, for instance, might work well for this type of application...depending on what the application for micro-flight there might be...

Radio waves and solar (think of that wingspan compared to the rest of it) would be pretty good options too (radio waves for flying at night). It'd involve technologies that don't currently exist.

It's great to see work here though. Humans are very good at beating nature on large scale items as it tends to get very inefficient as you scale up. But the small scale (especially since we're really a creature made of many small creatures) we lose big time, not only can a fruit fly generate power and fly with it's own controls, it can reproduce. Think about how far off we are making something that small that can do the same.

Considering the fact that evolution has had a few million years to develop these systems (fruit flies), I think giving us at least a decade or so to come up with something comparable is fair... That being said, it really is amazing how efficient nature actually is when it comes to getting things done.

Have them land on nearby humans every 5 minutes and siphon off some blood, for the glucose

In all seriousness, though, this thing just screams out for some form of wireless power delivery, perhaps using a\n EM field that the bugs can feed off. Lasers might be another energy source, but would require a lot of overhead to target correctly, and catching a bystander in a 1W laser beam is probably going to be more annoying than my aforementioned vampiric robo-fly.

The robot engineers are getting better at mimicking nature on things like wing movements; now they need to figure out how to mimic nature on the energy situation. Artificial metabolism with a small, light food supply perhaps?

I'm curious as to where the biggest gap is, given there are two parts to the equation - generating energy, and consuming energy. Is it that our constructions can't generate energy efficiently enough, or is it that they don't consume efficiently enough? (Or both, of course)

I'm a total void on this stuff, would be interested to learn more. I may be thinking about it all wrong, or using the wrong terms; but is it that we often do electrically what is done by nature chemically, and that is part of the inefficiency?

As others pointed out: energy production and storage is the number one factor that limits our progress, from tiny robots, to cars to space flight. I am also rather pessimistic that we will see a significant breakthrough in the coming decades.

Another concern though is - what are the implications if they do succeed? Governments for example will want to use these devices to spy on people or worse, perhaps some sort of assassination mini-robot.

Another concern though is - what are the implications if they do succeed? Governments for example will want to use these devices to spy on people or worse, perhaps some sort of assassination mini-robot.

This. These are cool! Not only will we have surveillance drones above our homes, but surveillance gnats inside them! Trevor Goodchild would love these.

I think a big part of that "deftly avoiding a striking hand" thing is that they're so light, the airflow drives them out of the way to safety. They're not really that smart, in other words, just lucky. I know it's hard to smash a drosophila melanogaster between hands, but much easier when using something that doesn't generate the same kind of air pressure, like a screen.

Producing flying machines at this scale is, from a technical perspective, super cool and, as the creators and the article notes, very dependent on biomimetics. Very small flying beasts live in a very different physical world to that which we live in; to them, air is quite syrupy, and the small ones doesn't so much fly as row through the air. I think I'm right in recalling that in fruit flies, the flight muscles act internally on the thorax, deforming it in "clicks" a bit like you can sometimes do with a tin can. The wings are attached in a relatively rigid way to the surface of the thorax. So relatively short muscle contracts result in quite large sweeps of the wing. Yes, their nervous systems are pretty simple, but I don't think it's yet been mapped in the same way as say, C. elegans, and it's complex enough for people to use fruit flies to model some human diseases of neurodegeneration.

It's ruining a number of sci-fi futures, Halo, Forever War, Gundam. The only show that addressed the problem (at first) was Neon Genesis Evangelion, where sky scraper sized armoured suits run about with a power tether attached.

Let’s imagine, if situation had been similar over hundred years ago, when Morgan began doing Drosophila work. How the ignorant fools would have laughed at someone who wanted to study fruit flies. Of all the things, do research on fruit flies? Imagine that! Surely no ground breaking, security enhancing stuff could come out if it. Nothing that would help us design better bread toasters.

Since Morgan’s time studying those small flies has yielded amazing amount of stuff linked to biotech, medicine, Nobel prizes and now flying little robots.

Freaking tiny flying robots!!!!!!

It all started over hundred years ago and at the time it would not have passed any ridiculous benefit analysis. Basic and fundamental scientific research rocks.

I'm a total void on this stuff, would be interested to learn more. I may be thinking about it all wrong, or using the wrong terms; but is it that we often do electrically what is done by nature chemically, and that is part of the inefficiency?

I'd be interested in knowing too. If you could fuel a cloud of tiny bots with a beaker of honey, that would be amusing but brilliant too I'm sure.

Considering the fact that evolution has had a few million years to develop these systems (fruit flies), I think giving us at least a decade or so to come up with something comparable is fair... That being said, it really is amazing how efficient nature actually is when it comes to getting things done.

A million monkeys on a million typewriters ...

Nature has had an awful lot of time to make prototypes .. and I bet the VAST majority of those have failed .. We only see the winning designs

They aren't beat. Being beat implies there was ever a race and that engineers had/have a chance of "winning" it. Humans will never "win" against Creation. We are like a bunch of children playing make believe with what we think we know and being impressed with how smart we are. Right...

Still very cool achievement.I want these guys and Roomba to get together and develop a swarm of these programmed to hunt and kill all the mosquitoes and ants in a defined area (my property). Use the insects as fuel to destroy more insects!

The robot engineers are getting better at mimicking nature on things like wing movements; now they need to figure out how to mimic nature on the energy situation. Artificial metabolism with a small, light food supply perhaps?

It may come down to a race between technology that provides that piece and technology that hijacks or replaces an insect's brain with a control system that will make it do what we want it to do instead of what an insect normally does. Imagine a programmable species of insect, or an implant that when installed on an insect, controls its brain.

Considering the fact that evolution has had a few million years to develop these systems (fruit flies), I think giving us at least a decade or so to come up with something comparable is fair... That being said, it really is amazing how efficient nature actually is when it comes to getting things done.

A million monkeys on a million typewriters ...

Nature has had an awful lot of time to make prototypes .. and I bet the VAST majority of those have failed .. We only see the winning designs

edit - except for the duck-billed platypus ..

Every living thing, you and me included, is descended from an unbroken line of billions of successful trials.

Another concern though is - what are the implications if they do succeed? Governments for example will want to use these devices to spy on people or worse, perhaps some sort of assassination mini-robot.

Another concern though is - what are the implications if they do succeed? Governments for example will want to use these devices to spy on people or worse, perhaps some sort of assassination mini-robot.

This. These are cool! Not only will we have surveillance drones above our homes, but surveillance gnats inside them! Trevor Goodchild would love these.

It sounds like it's time to add tin foil to the home insulation stack. Forget a tinfoil hat, I have a tinfoil house. Never mind that I get no cell phone reception.

Another concern though is - what are the implications if they do succeed? Governments for example will want to use these devices to spy on people or worse, perhaps some sort of assassination mini-robot.

This. These are cool! Not only will we have surveillance drones above our homes, but surveillance gnats inside them! Trevor Goodchild would love these.

It sounds like it's time to add tin foil to the home insulation stack. Forget a tinfoil hat, I have a tinfoil house. Never mind that I get no cell phone reception.

You're right, feeling violated at this point is silly. I should save my outrage for when it's actually happening. That way, my voice of dissent will be drowned out when the successor to the Google Glass is the Google Ghost! Without the distateful visual indicator of the voyeur strapped to my companions faces, I know I can trust them. Plus, it's *made* to be hackable... what's the problem?

“OK, Ghost. Follow him. I only want footage of he entering his PIN.”

Oh wait—we'll be using biometrics for that by then. Pfft, yeah... I dunno what concerns one could possibly have!

Another concern though is - what are the implications if they do succeed? Governments for example will want to use these devices to spy on people or worse, perhaps some sort of assassination mini-robot.

The answer to the power issue is the same as for all natural systems; eat. Only birth systems contain enough on-board power to sprout or hatch. When the robot can eat it's power source, we're golden. fuel-cell or induction charging would be the best approach. But to do useful work, it must eat.